Remote controllers have been known that operate any electronic devices, including electric appliances such as television sets, audio devices, and lighting apparatuses, by remote control. A remote controller of this type consists of a palm-sized operation module contained in a small casing and a controller provided within an electronic device to be controlled and operated. The controller is consistently supplied with electric power so as to be kept ready for receiving a control signals from the operation module.
Tire monitoring systems have also been known in which a sensor is provided for each tire and the conditions of the tire that are detected by the sensor are wirelessly transmitted over a communication circuit to a monitor provided in the vicinity of the driver's seat of a vehicle and displayed for ready monitoring of the conditions of tires of the vehicle at the driver's seat.
Most tire monitoring systems of this type use a battery (a storage battery or dry cell) as a power supply for the sensor because the sensor circuit provided in their sensor unit consumes more electric power than their communication circuit. If a sensor that operates on a battery is used, the battery must be replaced, or recharged if the battery is a secondary battery, before it becomes exhausted because battery exhaustion would stop the operation of the sensor. If a battery is exhausted frequently, it takes a lot of trouble to replace or recharge the battery, therefore measures are taken for minimizing battery drain.
For example, in a sensor disclosed in Japanese Patent Laid-Open No. 3-154999, means is provided that supplies power to a receiving module only for a predetermined time period at predetermined time intervals to operate it and supplies power to a sending module only during transmission in order to minimize battery drain.
In a sensor disclosed in Japanese Patent Laid-Open No. 2-268027, timing for receiving an interrogation signal and sending a reply signal is controlled by a timer circuit and power supply to other circuits except the timer circuit is shut off unless the interrogation signal is to be received or the reply signal is required to be sent so that battery drain is minimized.
However, the conventional remote controllers described above are not in keeping with energy saving commonly demanded today because a controlling unit provided within an electronic device is constantly supplied with power and thus a large amount of electric power is unnecessarily consumed.
The tire monitoring systems described above also waste battery power in their sensors during a time period in which monitoring of the conditions of tires is not required, that is, the vehicles are not used.
In light of the problems described above, an object of the present invention is to provide an electronic device starter that does not waste electric power while the device is not being used and a vehicle tire monitoring system in which the electronic device starter is used to eliminate unnecessary battery power consumption in its sensors.